Cavity resonator of rectangular prismatic shape



June 20, 1950 K. F. NIESSEN 2,512,368

CAVITY RESONATOR OF RECTANGULAR PRISMATIC SHAPES Filed Jan. 21, 1948 X i I l AZ I 1, i

l fl/GH'fREQl/EA/C Y I ENERGY INPUT F/ EE 1 CA V/TY RESONATOR i z I I c /,.f 4k r A W\ 45 B Y B A REL EZZZZDERZZ NZLSSZZW.

.JNL ENTOR.

Patented June 2Q, 1950 a UNITED STATES PATENT :CAVITY RESONATORDF RECTANGULAR -I= PRISMATIQSHPE i j. Karel Frederikv Niessen, Netherlands,

assignor to Hartford Na Company, Hartford, Conn, as trustee Application January 21, 1948, Serial No.

tional Bankvandflrust, I

In the Netherlands February 14, 1947 3 Claims. (01. 178-44) This invention relates to a cavity resonator of rectangular prismatic shape. Consequently, the space enclosed by the walls of the resonator has the shape of a rectangular prism. A rectangular prism is a body which is bounded by at least three planes parallel to a determined line and by two planes normal to this line. A cross-section normal to this line is termed perpendicular crosssection and the dimension parallel to this line is called the height of the prism.

Cavity resonators of this kind are known in which the perpendicular cross-section of the prism has a square or rectangular shape.

The cavity resonator according to the invention exhibits the characteristic that the perpendicular cross-section of the prism is a parallelogram having an angle of 45 and sides in a length ratio of 1:\/

For the lowest natural frequency for which the electrical field strength is independent 'of the height co-ordinate, this cavity resonator appears to exhibit a circuit of higher quality with respect to the above-mentioned conventional resonators at the same corresponding lowest natural frequency, the same height of the prism and manufactured from similar material. A detailed exposition of the theory underlying the behavior of the cavity resonator in accordance with the invention, as distinguished from resonators having a transverse cross-section of square or rectangular shape, may be found in the article On a Cavity Resonator of High Quality for the Fundamental Frequency, by K. F. Niessen, in the publication Applied Scientific Research, volume Bl-No. 1-1947, pages 18 through 34.

In order that the invention may be clearly understood and readily carried into efiect, it will now be described more fully by reference to the accompanying drawing.

The figure shows a cavity resonator according to the invention in parallel projection, use being made of the rectangular system of axes AX-Y-Z. The cavity resonator is in this case built up from thin plates of conductive material and has the shape of a rectangular prism. All the lateral faces AB--F-E, BCGF, CDI-IG and ADH-E are parallel to the X-axis, whereas the two faces A BC-D and EFGH are normal to the X-axis. The perpendicular cross-section of this prism, for example of the bottom face 2 in the figure, is a parallelogram, of which the angle B-AD is 45 and the sides AB and A-D are in the proportion of 1: /2

This cavity resonator may be used with advantage if, as is mostly the case, it is desired to utilize the lowest natural frequency for a desired manner of oscillation of a resonator and furthermore a high quality of circuit is required. It may be mentioned that the lowest natural frequency for the envisaged manner of oscillation of the cavity resonator which is obtained by dividing the first-mentioned resonator, by means of a conductive wall into two equal parts. With respect to the cavity resonator ABDEF-H, the volume of the cavity resonator AB CDEF-G--H is twice as large at the same lowest natural frequency for the said manner of oscillation. This results in a higher circuit quality Q1, which appears to be even higher than the quality Q2 of the circuit of a cavity resonator of rectangular prismatic shape having a square perpendicular section and even higher than the quality Q3 of the circuit of a cylindrical cavity resonator, the perpendicular cross-section of which is circular in shape and which is bounded on each side by planes normal to the axis of the cylinder, all this at the same height and. the same lowest natural frequency for the manner of oscillation here considered. With a height which is considerable as compared with the largest dimension of the perpendicular cross-section, the ratio of the qualities Q1, Q2, Q3 of the circuits was'found to be: Q1:Q2:Qs=2.93:1.58:1.7l.

What I claim is:

1. A cavity resonator adapted to sustain highfrequency electromagnetic oscillations comprising an enclosed conductive chamber for sustaining high frequency oscillations, said chamber being in the form of a six-sided prism having rectangular faces and a transverse cross section in the form of a parallelogram including diametrically opposed 45 degree angles and sides in a length ratio of 1: /2.

2. A cavity resonator adapted to sustain highfrequency electromagnetic oscillations comprising an enclosed chamber for sustaining high frequency oscillations, said chamber being constituted by conductive planar walls arranged to define a six-sided prism, said prism consisting of two pairs of rectangular face walls and one pair of end walls, each of said end walls being shaped as a parallelogram having diametrically opposed 45 degree angles and sides whose lengths exhibit a ratio of In/Z 3. A cavity resonator adapted to sustain high- Irequency electromagnetic oscillations compris ing an enclosed chamber for sustaining high frequency oscillations, said chamber being constituted by conductive planar walls arranged to define a six-sided prism, said prism consisting of two pairs of rectangular'face walls and-one- Number 4 pair of end walls, each of said end walls being shaped as a parallelogram having diametrically opposed 45 degree angles and sides whose lengths exhibit a ratio of 1: /2-, and means to excite said chamber with high frequency energy.

KAREL FREDERIK NIESSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date 23151313 Buchholz Mar. 30, 1943 

